You can lock selected tracks to prevent further editing from being performed on them.
The middle row of the Track Selector panel displays the Sync Lock icon (slash mark) for sync-locked tracks, and the Lock icon (padlock) for locked tracks.
Locking tracks to prevent further editing is especially useful in the following circumstances:
For more information about sync-locking tracks, see
Sync Locking Tracks.
The Lock icon indicates that the selected tracks are locked; no further
editing can occur on locked tracks.
The Lock icon disappears and the tracks are unlocked.